A hoax is a lie or falsehood that is deliberately made in order to pass as the truth. Therefore, a hoax is usually spread by people who believe it to be true, which makes it different from a joke or a prank.
A hoax could help change people's opinions about a political and social issue because it could convince them of a false perspective. By doing so, people could think about an issue in a way that is unfair, or biased, and that benefits a particular group.